*3.1.10. Use of immune boosters*

There are many substances that have been used in poultry for immune stimulation. Some of them are vitamin E, selenium and levamisole [33, 34]. The selenium supplementation has effect on enhancing humoral immune response in chicks [35, 36]. The selenium supplementation increased natural resistance of increasing response of organisms to antigenic stimuli [37, 38]. The increased humoral antibody titers are observed when selenium is used in feed [39].
